As a measure for improving viewing angle dependence of gamma characteristics in liquid crystal display devices (for example, holding down excess brightness and the like in a screen), a liquid crystal display device has been proposed which controls a plurality of sub-pixels in one pixel to have different brightness, so as to display a halftone by area coverage modulation of these sub-pixels (pixel division mode; for example, see Patent Literature 1).
As shown in FIG. 44, an active matrix substrate disclosed in Patent Literature 1 has a pixel region provided between two adjacent gate bus lines 112; a pixel electrode 121a disposed in an upper end part (part adjacent to one of the two gate bus lines) of the pixel region; a pixel electrode 121b disposed midway of the pixel region; and a pixel electrode 121c disposed in a lower end part (part adjacent to the gate bus line adjacent to the one of the two adjacent gate bus lines) of the pixel region. The pixel electrode 121a and the pixel electrode 121c are connected to a wire 119 for drawing out a source, which wire 119 is drawn out from a source electrode 116s of a transistor 116. The wire 119 is connected to a control electrode 118, which overlaps the pixel electrode 112b via an insulating layer. The middle pixel electrode 121b is coupled, via capacitor, with the pixel electrodes 121a and 121c (capacitor-coupled type pixel division mode). In a liquid crystal display device including this active matrix substrate, sub-pixels corresponding to the pixel electrodes 121a and 121c serve as bright sub-pixels, and a sub-pixel corresponding to the pixel electrode 121b serves as a dark sub-pixel. Hence, a halftone is displayed by area coverage modulation of the bright sub-pixels (2 sub-pixels) and the dark sub-pixel (1 sub-pixel).
It is known that, in such a liquid crystal display device employing a capacitor-coupled type pixel division mode, image-sticking is caused to the sub-pixel including the pixel electrode 121b, due to effects of electric charge stored in the pixel electrode 121b which is coupled, via capacitor, with the pixel electrodes 121a and 121c. 
Specifically, for a pixel electrode 61b, which is directly connected to a source line 55 via a transistor 56 as shown in FIG. 45, the following operation is carried out: In each frame, the transistor 56 is turned on, so that the pixel electrode 61b and the source line 55 are electrically connected to each other. Consequently, electric charge stored in the pixel electrode 61b while the transistor 56 is turning off is flown into the source line 55 while the transistor 56 is turning on. As a result, a direct-current voltage component hardly remains in the pixel electrode 61b, whereby image-sticking is rarely caused to the pixel electrode 61b. On the other hand, a pixel electrode 61a, which is coupled, via capacitor, with the pixel electrode 61b, keeps holding electric charge stored in the pixel electrode 61a even when the transistor 56 is turned on. Consequently, a direct-current voltage component remains in the pixel electrode 61a, whereby image-sticking is caused to the sub-pixel including the pixel electrode 61a. 
As an example of a method for solving the problem of image-sticking, Patent Literature 1 discloses the active matrix substrate in which the pixel electrode 121b, which is coupled, via capacitor, with the pixel electrode 121a, is provided away from the gate bus line 112 (see FIG. 44). That is, the pixel electrode 121b is provided between the pixel electrode 121a and the pixel electrode 121c so that electric charge would not flow into the pixel electrode 121b due to a direct-current voltage component of a signal passing in the gate bus line 112. This makes it possible to prevent image-sticking.
However, according to the configuration, the pixel electrode 121b remains in a floating state, and accordingly it is not possible to completely prevent electrical charge from flowing into the pixel electrode 121b. Therefore, it is difficult to achieve a display with high quality.
Moreover, Non-patent Literature 1 discloses a configuration in which a pixel electrode in a floating state as above is directly connected to a source line via a transistor. FIG. 46 is an equivalent circuit diagram illustrating a part of a liquid crystal panel described in Non-patent Literature 1. According to the liquid crystal panel shown in FIG. 46, pixel regions (main region and sub region) are provided between two adjacent gate bus lines; a main pixel electrode corresponding to the main region is connected to a source line (data line) via a first transistor (main-TFT); and a sub-pixel electrode corresponding to the sub region is connected to the source line via a second transistor (sub-TFT). Further, the first and second transistors are connected to an identical gate bus line (gate line).
According to the configuration, when the first and second transistors are turned on, the source line and the sub-pixel electrode are electrically connected to each other, and accordingly electric charge stored in the sub-pixel electrode is discharged (refreshed). This makes it possible to prevent image-sticking of the sub-pixel including the pixel electrode in a floating state.
Patent Literature 1    Japanese Patent Application Publication, Tokukai, No. 2006-39290 (Publication Date: Feb. 9, 2006)
Non-Patent Literature 1    SID 07 DIGEST on page 1010 through 1013